The increasing demand for reliable process cooling systems for battery manufacturing is directly linked to the rise of electric vehicles. As EV manufacturers strive to improve vehicles’ performance and efficiency, thermal management of batteries has become essential.
This is particularly true with the adoption of high-capacity lithium-ion battery packs in modern EVs, as well as modern processes such as rapid charging. These require effective cooling during the manufacturing process.
Battery cells’ performance and safety are at the heart of vehicle systems, including their lifespan. With the IEA expecting a 36% growth of annual electric car sales in the 2020s decade, guaranteeing a robust cooling system remains essential to deliver the required quality during the production of the process.
Current options are diverse, and involve innovative approaches such as modular chillers for battery production factories. But what are key cooling requirements and the available options today? Let’s have a look.
Battery cooling system: what is it and why it’s important
A battery cooling system is a mechanism designed to regulate battery temperatures.
This regulation is key during various applications and processes, including charging and discharging cycles, where batteries generate heat due to internal resistance and chemical reactions. While higher temperatures can provoke better short-term performance, they have a negative impact on their lifespan. On the other hand, lower temperatures decrease battery performance.
At the same time, ambient temperature variations can negatively impact battery performance. This is true of various battery models, including lithium-ion (Li-ion), nickel-cadmium (NiCd), and nickel-metal hydride (NiMH) cells.
Excessive heat or cold can degrade battery performance, shorten their lifespan and involve safety hazards (fire or thermal runaways).
As such, effective cooling systems are essential throughout the entire lifecycle of batteries, from production to their use in vehicles. Here are some crucial moments in which battery cooling is fundamental:
- During electrode coating and formation process, facilitating the bonding of electrode materials
- During cell assembly, as some electrolytes require specific temperature conditions
- In quality control processes, including thermal cycling tests that seek to simulate real-world conditions to evaluate performance and reliability
- During charging of electric vehicle batteries, cooling systems dissipate heat to prevent overheating
- In discharging processes, particularly during high-power demand processes such as acceleration
- Counteracting high ambient temperatures, so that the battery cooling system mitigates the effects of external heat
Battery cooling ensures batteries maintain optimal temperature ranges.
Battery cooling system for EVs: the key requirements
The ideal battery cooling system is able to deploy cooling capacities where and when it’s needed, responding to battery demands in the most precise way possible.
The following are some of the characteristics incorporated into the most advanced battery cooling systems today:
- They should provide effective and stable temperature control within a narrow range.
- In the case of battery cooling systems during manufacturing, zoning capabilities would be advisable. This means different sections of the process can be controlled independently, allowing for different temperature conditions simultaneously.
- Energy efficiency. As electric vehicles advance towards a more sustainable future, battery cooling systems should aim at minimal energy consumption.
- Fast response time, quickly accommodating to changing thermal conditions in batteries. This is where equipment such as variable speed compressors within liquid cooling systems stand out, as they are able to adjust cooling capacities based on actual demand.
- Effectively address issues such as potential leaks and corrosion (only in liquid cooling systems) and aging (which typically sees bigger energy losses in the form of heat).
Current options for battery cooling systems for electric vehicles
Air cooling
These use fans or natural airflows to dissipate heat from the battery pack by circulating air around the batteries. This represents a relatively simple and cost-effective method, but presents important limitations in high-temperature environments or during processes such as rapid charging/discharging. This is why it’s been majorly displaced by other more efficient methods like liquid cooling.
Liquid cooling
This battery cooling system uses a coolant (such as water or a mixture of water and glycol) to absorb and carry away heat from the batteries. The coolant circulates through a closed-loop system consisting of a network of pipes or channels in direct contact with the battery cells, and relies on convective heat transfer: the coolant comes into direct contact with the heat source, absorbs heat, and carries it away through convection.
While these are more complex and costly than air-cooling methods, liquid cooling has proven to be much more efficient than air cooling. It also allows for precise temperature control and can manage high heat loads. These characteristics mean liquid cooling has been praised for developing successful battery cooling, particularly as the EV industry moves towards more complex battery developments.
Certain challenges of liquid cooling must also be addressed when designing a battery cooling system. As such, this option requires meticulous maintenance to avoid leaks and has proven to require a high level of hermeticity in battery packs. Additionally, some components in battery packs may not be compatible with liquid cooling, an issue that must be resolved by thermal engineering experts.
Refrigerant direct cooling
This method involves the circulation of a refrigerant through a closed-loop system in a battery pack to remove heat. As such, the heat transfer medium is a highly-effective refrigerant
These systems require more components compared to liquid cooling systems, as they may require additional components such as expansion valves, condensers, and evaporators.
Devising the right battery cooling system
Choosing the most appropriate battery cooling system represents a crucial choice, but cannot be guided by a ‘one-size-fits-all’ mentality. As such, factors such as the specific application and its desired performance must guide the decision towards the most appropriate battery cooling technique.
In the meantime, engineers face a number of challenges to maximize the batteries’ efficiency, responsiveness and reliability. Cost-effectiveness remains a crucial factor, including considerations surrounding maintenance needs.
As the industry moves forward, battery cooling will remain a crucial element for advancing towards greater performance and faster charging rates, all while ensuring safety and longer battery lifespans.
At ARANER , we put our thermal engineering expertise to work in advancing towards the battery cooling system of the future. As such, efficiency and sustainability are two of the key axes guiding our state-of-the-art cooling solutions, including our district cooling line.
Would you like to learn more about our battery cooling projects and how we can help you access the right system for your batteries? Download our district energy ebook to discover more about our cooling solutions and get in touch with us and speak to our team about how we can help you.
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